4107 Allison cradle cracked

[sdc53]

Hey guys,
Need someone with a 4107 to post pics of the area on the curb side rear door lower hinge corner area.  PO converted mine to an Allison trans, need to know if this transmission support bar was present on a stock 4107 and/or of this is an alteration to support the Allison trans that was added.  It doesn't look stock.  Mine is cracked, I can stick a jack on it and re-weld it but something just doesn't seem right here and I don't particularly care for the way this was done and it'll probably just break again unless I do something better or different here.  Also note the adjacent rivets that have been making a groove here for themselves.
Here's pics of the situation, look at the lower right corner of the open door.  Pics get progressively closer to the area.
Overall view

A little closer

Rivets at corner

Broken weld at support bar


There are a couple of bolts (only one really pictured) that appear to sandwich a vertical bar to the body near the door hinge that comes down and is (was) bent to come around under this horizontal piece under the tranny.  The other end of the horizontal bar is bolted to the bumper.  Before anyone asks, I've never towed anything with this bus, and I've only had it about 9 months.

Advice and pictures of correct setups are welcomed..

Scott
'69 4107
Gladstone, OR

[TomC]

When AMGeneral created my transit from the Canadian Flyer, AMGeneral converted the inline drive train to a V drive like all other US buses. Hence the first series of AMGenerals had numerous cracks on the engine cradle since the weight distribution is so off compared to the inline engine. My B series has numberous fish plates, or little triangular plates welded at many of the corners.

You probably should do the same. Weld it up and then reinforce it with a triangular plate welded in. There is a lot of torquing at the transmission. Good Luck, TomC

[sdc53]

Yes, I'm going to reinforce it with a 45 there, but its going to be hard because the plate that is busted comes up behind the hinge area there.  Not sure if I should tie it in with the other piece that heads away towards bulkhead cradle attach point, because it looks like that piece is allowed to move and float separately from the broken one currently. It would be stronger if I did that, but not sure if it would be right - I wonder if it is supposed to he able to move independently.

[travlinman]

Scott

My 4106 has been converted to a Allison so here are are a few photos of my set up. The first two are from above and the last is from the outside. Hope this helps.

TM

[luvrbus]

I have a good 4107 cradle if you need one Red Ryder left it at my place in AZ yours for free if someone will pick it up in AZ

[sdc53]

Thanks TM and Clifford.

[wildbob24]

Scott,

Attached is a line drawing from the 4107 parts manual. There is no transmission support shown. Most V730 conversions I've seen had one added since the auto is so much heavier than the manual.

As much as your bracket has dropped down at the break, I'd take a careful look at the motor mounts and make sure they're OK.

Bob

[sdc53]

Bob,
Thanks for the manual pic.  Motor mounts look fine. Concerned about the bell housing, but the Allison mount has some flex to it and it seems to be helping in that regard. It's somewhere around 3/16" off at one end, which translates to far less at the mount point which is in the center.  It is resting on another cross-member so it is not falling any further.

Got a plan to fix brewing, it involves some L shaped steel angle iron cut like a picture frame corner with a 45 piece of flat stock welded on one side to reinforce, and that assembly welded to the support member and bolted in place using the same holes as the one that failed.

Scott
'69 4107

[Bill B /bus]

If memory is some what correct the factory V730 installs had an additional brace under the transmission to carry the a extra weight of the auto. Someone may be able to find the factory manual pictures. Mine went when the Buffalo was sold so unable to prove memory true or not.

Bill

[luvrbus]

I have a GM manual that shows a brace for the 730 with a air bag and a regulator in a transit model I never knew GM used a 730 in a transit model till looking at some of the manuals I have in my possession to sell for a friend 

Looked to me like GM kept it simple there is very little difference in all the manuals it looks like the 1's for a transit model are about the same as the high way coaches expect for a few items and pictures,the GM manual X7563 covers 9 different models

Keep your eyes on Ebay as soon as I get 8 tubs of manuals sorted out they are going up for sale I never saw a collection of manuals like this before buses, transmission, engines,brakes,turbos,Ac and ECM's 

Sammy had quite the collection of manuals no reason the guy could answer about any question asked so accurate   

[chessie4905]

I dismantled a Flxible city bus (6v-71 &V730) a couple years ago that had a similar brace as you had pictured, but it had a small air bag with a pressure regulator attached to the air line to it. I'm going to install/modify it, as necessary to go on my 4905, just for insurance.

[sdc53]

I'd still like to see some pics of how it should be done properly on a 4107 then, seems like there may be better ways.  The 4106 pics posted were not correlating well to my situation.  Not sure I buy into the airbag support, as the tranny still needs support when just sitting there, if the airbag were deflated it would put extra stress on the bell housing.

Thanks much,
Scott
'

[chessie4905]

The V730 is designed to hang off the engine with no additional support;just the rear engine mounts. The extra brace with air bag was added by some bus companies, mostly city operations, to absorb severe shock from situations such as severe pot holes, which was causing bell housing bolt failures/leaks, body/bulkhead cracks, and in unusual situations cracks in trans cases. You don't want an additional firm support to the trans because of stress between trans and rear engine mounts. If you notice, all vehicles use a three point support on engine and trans. Btw, my 4905 has no trans support, it hangs off the engine, same as my other 4905 with manual transmission.